We use the results from recent computations of updated non-linear convective pulsating models to constrain the distance modulus of Galactic globular clusters through the observed periods of first overtone ( RR _ { c } ) pulsators .
The resulting relation between the mean absolute magnitude of RR Lyrae stars < M _ { V } ( RR ) > and the heavy element content [ Fe / H ] appears well in the range of several previous empirical calibrations , but with a non linear dependence on [ Fe / H ] so that the slope of the relation increases when moving towards larger metallicities .
On this ground , our results suggest that metal-poor ( [ Fe / H ] < -1.5 ) and metal-rich ( [ Fe / H ] > -1.5 ) variables follow two different linear < M _ { V } ( RR ) > - [ Fe / H ] relations .
Application to RR Lyrae stars in the metal-poor globular clusters of the Large Magellanic Cloud provides a LMC distance modulus of the order of 18.6 mag , thus supporting the “ long ” distance scale .
The comparison with recent predictions based on updated stellar evolution theory is shortly presented and discussed .